title: Characterization of an F1 deletion mutant of Yersinia pestis CO92, pathogenic role of F1 antigen in bubonic and pneumonic plague, and evaluation of sensitivity and specificity of F1 antigen capture-based dipsticks.
abstract: We evaluated two commercial F1 antigen capture-based immunochromatographic dipsticks, Yersinia Pestis (F1) Smart II and Plague BioThreat Alert test strips, in detecting plague bacilli by using whole-blood samples from mice experimentally infected with Yersinia pestis CO92. To assess the specificities of these dipsticks, an in-frame F1-deficient mutant of CO92 (Δcaf) was generated by homologous recombination and used as a negative control. Based on genetic, antigenic/immunologic, and electron microscopic analyses, the Δcaf mutant was devoid of a capsule. The growth rate of the Δcaf mutant generally was similar to that of the wild-type (WT) bacterium at both 26 and 37 °C, although the mutant's growth dropped slightly during the late phase at 37 °C. The Δcaf mutant was as virulent as WT CO92 in the pneumonic plague mouse model; however, it was attenuated in developing bubonic plague. Both dipsticks had similar sensitivities, requiring a minimum of 0.5 μg/ml of purified F1 antigen or 1 × 10(5) to 5 × 10(5) CFU/ml of WT CO92 for positive results, while the blood samples were negative for up to 1 × 10(8) CFU/ml of the Δcaf mutant. Our studies demonstrated the diagnostic potential of two plague dipsticks in detecting capsular-positive strains of Y. pestis in bubonic and pneumonic plague.
authors.affiliation: Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas 77555-1070, USA.
authors.forename: Jian
authors.initials: J
authors.lastname: Sha
authors.forename: Janice J
authors.initials: JJ
authors.lastname: Endsley
authors.forename: Michelle L
authors.initials: ML
authors.lastname: Kirtley
authors.forename: Sheri M
authors.initials: SM
authors.lastname: Foltz
authors.forename: Matthew B
authors.initials: MB
authors.lastname: Huante
authors.forename: Tatiana E
authors.initials: TE
authors.lastname: Erova
authors.forename: Elena V
authors.initials: EV
authors.lastname: Kozlova
authors.forename: Vsevolod L
authors.initials: VL
authors.lastname: Popov
authors.forename: Linsey A
authors.initials: LA
authors.lastname: Yeager
authors.forename: Irina V
authors.initials: IV
authors.lastname: Zudina
authors.forename: Vladimir L
authors.initials: VL
authors.lastname: Motin
authors.forename: Johnny W
authors.initials: JW
authors.lastname: Peterson
authors.forename: Kristin L
authors.initials: KL
authors.lastname: DeBord
authors.forename: Ashok K
authors.initials: AK
authors.lastname: Chopra
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000032:analysis* / Q000235:genetics / Q000378:metabolism; D019411:Clinical Laboratory Techniques / Q000379:methods*; D004195:Disease Models, Animal; D005260:Female; D017353:Gene Deletion; D007118:Immunoassay; D051379:Mice; D008807:Mice, Inbred BALB C; D010930:Plague / Q000175:diagnosis* / Q000382:microbiology / Q000401:mortality / Q000473:pathology*; D011933:Reagent Kits, Diagnostic; D012680:Sensitivity and Specificity; D016019:Survival Analysis; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics* / Q000378:metabolism; D015010:Yersinia pestis / Q000235:genetics / Q000254:growth & development / Q000472:pathogenicity*
chemical_list: D001426:Bacterial Proteins; D011933:Reagent Kits, Diagnostic; D037521:Virulence Factors; C086725:caf1 protein, Yersinia pestis